1. Field of the Invention
The present invention relates to a pad conditioner, a pad conditioning method, and a polishing apparatus, in particular, a pad conditioner which recovers a surface of a polishing pad in a polishing apparatus for polishing a work such as a semiconductor wafer, a pad conditioning method, and a polishing apparatus which is provided with the pad conditioner.
2. Description of the Related Art
As microstructure and multilayered structure of a semiconductor device have been achieved, CMP (Chemical Mechanical Polishing) technology has become essential in a manufacturing process of the semiconductor device. The CMP technology is now used for planarization of an insulating film between layers, as well as in various processes of Cu wiring and isolation of elements, for example.
In the CMP technology for planarization, removal rate uniformity (polishing uniformity) across a work surface is an important specification. In order to improve the polishing uniformity, it is important to uniformly distribute any elements which affect the removal rate across a work surface.
While such important elements include a polishing pressure and a relative velocity in polishing, a surface state of a polishing pad is also an important element quantification of which is still in a preliminary stage. A preferable surface state of a polishing pad is achieved by conditioning the polishing pad. Also, a fact that, in a so-called in-situ conditioning in which a pad is conditioned during polishing, for example a stopping of the conditioning suddenly drops a removal rate, shows that a precise control of a surface state of a polishing pad is important.
Pad conditioning is an act to bring a pad conditioner (hereinafter, it may be simply referred to as a conditioner) having grinders such as diamond into contact with a polishing pad to scrape or roughen a surface of the polishing pad, so that a surface state of a new polishing pad is optimized as an initial state with a good holding capacity of the slurry or the slurry holding capacity of the polishing pad in use is recovered to maintain its polishing capability.
Conventionally, pad conditioners having diamond abrasive particles electro-deposited thereto have been often used to condition a polishing pad by being pressed against the polishing pad while rotating around its central axis (for example, see Japanese Patent Application Laid-Open No. 2001-274122, or Japanese Patent Application Laid-Open No. 2003-181756).
FIG. 12 is a conceptual view to illustrate a pad conditioner described in Japanese Patent Application Laid-Open No. 2001-274122: The pad conditioner 130 described in Japanese Patent Application Laid-Open No. 2001-274122 includes, as shown in FIG. 12, a substrate 131 having diamond abrasive particles 133 electro-deposited thereto, and a supporting section 132 to which the substrate 131 is fixedly attached.
FIG. 13 is a conceptual view to illustrate a pad conditioner described in Japanese Patent Application Laid-Open No. 2003-181756. The pad conditioner 130A described in Japanese Patent Application Laid-Open No. 2003181756 in principle includes a substrate 131A, diamond abrasive particles 133 which are electro-deposited to the substrate 131A, and a supporting section 132A, and the substrate 131A is swingably mounted to the supporting section 132A in every direction, via a so-called gimbal arrangement of a ball joint 132a for example, so as to follow a surface of a polishing pad 20.
Apparatuses having a brush conditioner in addition to a diamond conditioner are also known (for example, see Japanese Patent Application Laid-Open No. 2003-211355). Japanese Patent Application Laid-Open No. 2003-211355 discloses a diamond conditioner for scraping a polishing pad surface as a first conditioner and a brush conditioner for extracting foreign matters clogged in recesses in the polishing pad surface as a second conditioner.
Since the brush conditioner is for extracting foreign matters clogged in recesses in the polishing pad surface, it is the diamond conditioner of the first conditioner which conditions the pad.
The brush conditioner has a nylon brush as a brushing member. The nylon brush can brush a pad surface, but is not effective for scraping the pad surface.
Thus, in the technology disclosed in the above document, the brush conditioner is used as a device only for removing foreign matters in a pad surface, not for scraping and conditioning the pad surface with a brush.
Other than the above, there is another document which describes about conditioning by use of brush (for example, see the above Japanese Patent Application Laid-Open No. 2003-181756 or Japanese Patent Application Laid-Open No. 10-329003). However, both brushes described in Japanese Patent Application Laid-Open No. 2003-181756 and Japanese Patent Application Laid-Open No. 10-329003, as well as the one in Japanese Patent Application Laid-Open No. 2003-211355, are described to use in a brushing method for extracting foreign matters in a pad surface, not to use in a conditioning method for scraping a surface of a polishing pad.